Shielded enclosure having tortuous path seal

ABSTRACT

A modular system of plastic walls having embedded and coextensive electrically conductive components configured to electrically connect with each other when the walls are mated. The walls have joining edges that form joint seams with other walls when joined together to create an enclosure. When enough walls are used to surround a storage space, a Faraday cage is created. The walls additionally have portions of tortuous paths at each joining edge that mate with a complementary portion of a tortuous path of another wall when the walls are joined together. A torturous path seal is thereby created at each joint seam. The plastic walls can be configured in a multiplicity of combinations to create various enclosures necessary for RFID-enabled storage and tracking of medical articles. Containers, enclosures, cabinets, and drawers of differing heights and sizes can be made and they may be stacked or otherwise assembled.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional Application No.62/273,421 filed Dec. 30, 2015, the disclosure of which is incorporatedby reference in its entirety.

BACKGROUND

The invention relates generally to a container formed of anon-electrically-conducting substrate having an electrically-conductivecomponent so that the container has an RF shield to attenuate RF energyin the container from leaking out of the container, and moreparticularly, to an RF shield that includes a tortuous path seal.

As a general summary, in the field of medication administrationcontainers are used to store medications before administration to apatient. In RFID tracking systems of today, the medications include anattached RFID tag that responds to RFID interrogation energy. Whentaking an inventory of a container in which RFID-tagged medications arestored, it is important that the RF activation energy transmitted by anRFID reader to the container stay within the container. Otherwise,medications that have RFID tags located outside the container may beactivated by the transmitted RF energy and are read by the RFID reader.The results would therefore be inaccurate for an inventory of thecontainer because the reader would record that the medications outsidethe container are inside the container when they actually are not.Shielding the container so that RF energy transmitted into the containeris attenuated by the container's RF shield that it cannot activate anRFID tag outside the container is desired to avoid this problem.

Medication dispensing systems have been in use for many years. Theinitial purpose of such systems was to reduce medication errorsassociated with manual distribution and the high cost of maintaining alarge amount of inventory. Current systems present many advantages,including lower costs associated with pharmaceutical distribution,improved inventory control, substance control, automated documentation,further reduction of errors, and relieving professional pharmacists andnursing personnel of many tasks.

In large medical facilities, the main inventories of pharmaceuticalitems are held in storage locations which are often far removed from thepatients who use them. To facilitate secure and accurate delivery of thepharmaceutical items from these storage locations to the patient, avariety of systems have been proposed and put into use. In earliersystems referred to as “cart exchange” systems, medication carts aredistributed at nursing stations in the medical facility, remote from thecentral pharmacy, and are periodically exchanged with fully suppliedcarts. Typically, these carts contain a twenty-four hour supply ofmedications sorted by patient into specific drawers. The “used” cart isreturned to a central pharmacy supply area where the next twenty-fourhours of medications are replenished. Narcotics are stored in lockedboxes on the floor, requiring two nurses with separate keys and awritten log.

Radio-frequency identification (“RFID”) is the use of electromagneticenergy (“EM energy”) to stimulate a responsive device known as an RFID“tag” or transponder to identify itself and in some cases, provideadditionally stored data. RFID tags typically include a semiconductordevice having a memory, circuitry, and one or more conductive tracesthat form an antenna. Typically, RFID tags act as transponders,providing information stored in the semiconductor device memory inresponse to an RF interrogation signal received from a reader, alsoreferred to as an interrogator.

RFID tags may be incorporated into or attached to articles to betracked. In some cases, the tag may be attached to the outside of anarticle with adhesive, tape, or other means and in other cases, the tagmay be inserted within the article, such as being included in thepackaging, located within the container of the article, or sewn into agarment. The RFID tags are manufactured with a unique identificationnumber which is typically a simple serial number of a few bytes with acheck digit attached. This identification number is incorporated intothe tag during manufacture. The user cannot alter thisserial/identification number and manufacturers guarantee that eachserial number is used only once. This configuration represents the lowcost end of the technology in that the RFID tag is read-only and itresponds to an interrogation signal only with its identification number.Typically, the tag continuously responds with its identification number.Data transmission to the tag is not possible. These tags are very lowcost and are produced in enormous quantities.

Such read-only RFID tags typically are permanently attached to anarticle to be tracked and, once attached, the serial number of the tagis associated with its host article in a computer data base. Forexample, a particular type of medicine may be contained in hundreds orthousands of small vials. Upon manufacture, or receipt of the vials at ahealth care institution, an RFID tag is attached to each vial. Each vialwith its permanently attached RFID tag will be checked into the database of the health care institution upon receipt. The RFIDidentification number is associated in the data base with the type ofmedicine, size of the dose in the vial, and perhaps other informationsuch as the expiration date of the medicine. Thereafter, when the RFIDtag of a vial is interrogated and its identification number read, aprocessor will compare the identification number to the data base of thehealth care institution to match that identification number with itsstored data about the contents of the vial. The contents of the vial canthen be determined as well as any other characteristics that have beenstored in the data base. In this system, the institution maintains acomprehensive data base regarding the articles in inventory rather thanincorporating such data into each RFID tag separately.

An object of the RFID tag is to associate it with an article throughoutthe article's life in a particular facility, such as a manufacturingfacility, a transport vehicle, a health care facility, a storage area,or other, so that the article may be located, identified, and tracked,as it is moved. For example, knowing where certain medical articlesreside at all times in a health care facility can greatly facilitatelocating needed medical supplies when emergencies arise. Similarly,tracking the articles through the facility can assist in generating moreefficient dispensing and inventory control systems as well as improvingwork flow in a facility. Additionally, expiration dates can be monitoredelectronically and those articles that are older and about to expire canbe moved to the front of the line for immediate dispensing. This resultsin better inventory control and lowered costs.

Other RFID tags are writable and information about the article to whichthe RFID tag is attached can be programmed into the individual tag.While this can provide a distinct advantage when a facility's computerservers are unavailable, such tags cost more, depending on the size ofthe memory in the tag. Programming each one of the tags with informationcontained in the article to which they are attached involves furthertime and expense.

RFID tags may be applied to containers or articles to be tracked by themanufacturer, the receiving party, or others. In some cases where amanufacturer applies the tags to the product, the manufacturer will alsosupply a respective data base file that links the identification numberof each of the tags to the contents of each respective article. Thatmanufacturer supplied data base can be distributed to the customer inthe form of a file that may easily be imported into the customer'soverall data base thereby saving the customer from the expense ofcreating the data base.

Many RFID tags used today are passive in that they do not have a batteryor other autonomous power supply and instead, must rely on theinterrogating energy provided by an RFID reader to provide power toactivate the tag. Passive RFID tags require an electromagnetic field ofenergy of a certain frequency range and certain minimum intensity inorder to achieve activation of the tag and transmission of its storeddata. Another choice is an active RFID tag; however, such tags requirean accompanying battery to provide power to activate the tag, thusincreasing the expense of the tag and making them undesirable for use ina large number of applications.

Depending on the requirements of the RFID tag application, such as thephysical size of the articles to be identified, their location, and theability to reach them easily, tags may need to be read from a shortdistance or a long distance by an RFID reader. Such distances may varyfrom a few centimeters to ten or more meters. Additionally, in the U.S.and in other countries, the frequency range within which such tags arepermitted to operate is limited. As an example, lower frequency bands,such as 125 KHz and 13.56 MHz, may be used for RFID tags in someapplications. At this frequency range, the electromagnetic energy isless affected by liquids and other dielectric materials, but suffersfrom the limitation of a short interrogating distance. At higherfrequency bands where RFID use is permitted, such as 915 MHz and 2.4GHz, the RFID tags can be interrogated at longer distances, but theyde-tune more rapidly as the material to which the tag is attachedvaries. It has also been found that at these higher frequencies, closelyspaced RFID tags will de-tune each other as the spacing between tags isdecreased.

There are a number of common situations where the RFID tags may belocated inside enclosures. Some of these enclosures may have entirely orpartially metal or metallized surfaces. Examples of enclosures includemetal enclosures (e.g., shipping containers), partial metal enclosures(e.g., vehicles such as airplanes, buses, trains, and ships that have ahousing made from a combination of metal and other materials), andnon-metal enclosures (e.g., warehouses and buildings made of wood).Examples of objects with RFID tags that may be located in theseenclosures include loose articles, packaged articles, parcels insidewarehouses, inventory items inside buildings, various goods insideretail stores, and various portable items (e.g., passengeridentification cards and tickets, baggage, cargo, individual life-savingequipment such as life jackets and masks) inside vehicles, etc.

The read range (i.e., the range of the interrogation and/or responsesignals) of RFID tags is limited. For example, some types of passiveRFID tags have a maximum range of about twelve meters, which may beattained only in ideal free space conditions with favorable antennaorientation. In a more realistic situation, the observed RFID tag rangeis often six meters or less. Therefore, some of the enclosures describedabove may have dimensions that far exceed the read range of anindividual RFID tag. Unless the RFID reader can be placed in closeproximity to a target RFID tag in such an enclosure, the tag will not beactivated and read. Additionally, metal surfaces of the enclosurespresent a serious obstacle for the RF signals that need to be exchangedbetween RFID readers and RFID tags, making RFID tags located behindthose metal surfaces difficult or impossible to detect.

In addition to the above, the detection range of the RFID systems istypically limited by signal strength to short ranges, frequently lessthan about thirty centimeters for 13.56 MHz systems. Therefore, portablereader units may need to be moved past a group of tagged items in orderto detect all the tagged items, particularly where the tagged items arestored in a space significantly greater than the detection range of astationary or fixed single reader antenna. Alternately, a large readerantenna with sufficient power and range to detect a larger number oftagged items may be used. However, such an antenna may be unwieldy andmay increase the range of the radiated power beyond allowable limits.Furthermore, these reader antennae are often located in stores or otherlocations where space is at a premium and it is expensive andinconvenient to use such large reader antennae. In another possiblesolution, multiple small antennae may be used but such a configurationmay be awkward to set up when space is at a premium and when wiring ispreferred or required to be hidden.

In the case of medical supplies and devices, it is desirable to developaccurate tracking, inventory control systems, and dispensing systems sothat RFID tagged devices and articles may be located quickly should theneed arise, and may be identified for other purposes, such as expirationdates. In the case of medical supply or dispensing cabinets used in ahealth care facility, a large number of medical devices and articles arelocated closely together, such as in a plurality of drawers. Cabinetssuch as these are typically made of metal, which can make the use of anexternal RFID system for identification of the stored articlesdifficult. In some cases, such cabinets are locked due to the presenceof narcotics or other medical articles or apparatus within them that aresubject to a high theft rate. Thus, manual identification of the cabinetcontents is difficult due to the need to control access.

Providing an internal RFID system in such a cabinet can pose challenges.Where internal articles can have random placement within the cabinet,the RFID system must be such that there are no “dead zones” that theRFID system is unable to reach. In general, dead zones are areas inwhich the level of coupling between an RFID reader antenna and an RFIDtag is not adequate for the system to perform a successful read of thetag. The existence of such dead zones may be caused by orientations inwhich the tag and the reader antennae are in orthogonal planes. Thus,articles placed in dead zones may not be detected thereby resulting ininaccurate tracking of tagged articles.

Often in the medical field, there is a need to read a large number oftags attached to articles in such an enclosure, and as mentioned above,such enclosures have limited access due to security reasons. Thephysical dimension of the enclosure may need to vary to accommodate alarge number of articles or articles of different sizes and shapes. Inorder to obtain an accurate identification and count of suchclosely-located medical articles or devices, a robust electromagneticenergy field must be provided at the appropriate frequency within theenclosure to surround all such stored articles and devices to be surethat their tags are all activated and read. Such medical devices mayhave the RFID tags attached to the outside of their containers and maybe stored in various orientations with the RFID tag (and associatedantenna) pointed upwards, sideways, downward, or at some other angle ina random pattern.

It is a goal of many health care facilities to keep the use of EM energyto a minimum, or at least contained. The use of high-power readers tolocate and extract data from RFID tags is generally undesirable inhealth care facilities, although it may be acceptable in warehouses thatare sparsely populated with workers, or in aircraft cargo holds.Radiating a broad beam of EM energy at a large area, where that EMenergy may stray into adjacent, more sensitive areas, is undesirable.Efficiency in operating a reader to obtain the needed identificationinformation from tags is an objective. In many cases where RFID tags areread, hand-held readers are used. Such readers transmit a relativelywide beam of energy to reach all RFID tags in a particular location.While the end result of activating each tag and reading it may beaccomplished, the transmission of the energy is not controlled except bythe aim of the user. Additionally, this is a manual system that willrequire the services of one or more individuals, which can also beundesirable in facilities where staff is limited. In many such systems,the RFID reader is a portable unit with a “tethered reader head” therebyimposing the extra time and effort to find the unit, be sure it ispowered, take it to the medication cabinet where the inventory isrequired, open the cabinet, collect the inventory data, and then uploadthe inventory data to a pharmacy server. All of the foregoing can takesignificant amounts of time.

A problem often arises where only the RFID tags attached to medicalarticles located in a particular location or container are to be readfor inventory purposes. For example, a tray of medical articles mayexist with each of the articles in the tray having an attached RFID tag.Where the articles in the tray must be checked for possible expiration,it is common to activate the RFID tags in the tray by directing an RFIDreader's beam at the tray. This will activate the RFID tag on each ofthe medical articles in the tray. The activated RFID tags will transmittheir individual identification numbers which are received by the RFIDreader. Those received identifications are communicated from the RFIDreader to a processor that accesses a database to compare each receivedidentification number to a medical article in the database to determineif any are expired.

While this system works well, problems arise when the activating RFIDbeam was strong enough to reach the RFID tags on medical articles thatare stored in the locality of the tray but are not in the tray. The tagsof these remote articles will also be activated, they will transmittheir identification data, and the RFID reader will read theiridentifications, not knowing that those medical articles are not in thetray. If one of those medical articles having an activated tag that islocated outside the tray is determined to be expired, inaccuracy andtime wasting can result. Even though the tray itself does not have anyexpired articles in it, it will probably be removed from use because thereading process identified an expired article. Then each medical articlein the tray will now likely need to be visually inspected to determineif it is expired. The item that was reported expired will not be foundin the tray but the tray is unavailable for use until this discrepancyhas been found.

Consequently, manufacturers of RFID tracking systems strive to furnishan electrical isolation container also called an RF shielded container,within which the tray is placed before it is scanned. The RF shieldedcontainer is sometimes referred to as a Faraday cage and its sixmetallic and electrically connected walls greatly attenuate the passageof electrical energy into and out of the container. The RFID readerantenna(s) is placed inside the RF shielded container. However, theradiated signal will leak out of gaps, slots, openings, and otherdiscontinuities that may be present in the RF shielded container. Theseleaked signals are free to radiate in open space and may cause theactivation of remote RFID tags. Conversely, signals can travel into theRF shielded container in the same manner.

For RFID reading energy having higher frequencies, good shieldingeffectiveness can usually be achieved by the use of thin metal shieldingas the container material or lining, but the assumption is that theshield is continuous and fully surrounds the RFID-tagged articleswithout gaps or apertures. However, it has been found that gaps orapertures and other openings can be very difficult to avoid. Seamsneeded for manufacturing, doors, drawers, and other openings made forvarious purposes penetrate the shielded container, which can lower theshielding performance of the container. Welding, brazing, or solderingis used to make seams between sheets that are permanently secured. Themetal faces to be joined must be clean to promote complete filling ofthe seam with conductive metal. Screws or rivets are less satisfactorymethods to secure the seams because permanent low-impedance contactalong the seams between the fasteners is difficult to maintain withthese methods. A total lack of contact along any part of the seamresults in a thin gap capable of acting as a slot antenna. Such anantenna transmits energy at wavelengths shorter than about four timesthe gap length.

Radio frequency (“RF”) activation energy transmitted within the walls ofa Faraday cage container is greatly attenuate at the walls and verylittle if any energy will leak from that container. As a result only theRFID tags in the isolation container are read. This can then solve theproblem of inadvertently reading remote RFID tags that are not in thecontainer; however, making and distributing RF shielded containers haveassociated problems, some of which have been described above.

In medical applications, current systems used for tracking items withRFID technology consist of heavy, sometimes custom made, and moreexpensive, metal containers. These metal containers are basic in designdue to the cost and difficulty of shaping metal into aestheticallypleasing shapes. These containers consist of sheet metal that has beenbent into shape and then welded to form an enclosure. The enclosures arefabricated by hand and therefore are expensive. The sheet metalenclosures are also relatively heavy and therefore require expensivehardware for stacking multiple units or to mount under cabinets, desks,and work stations. The design of the enclosures is that of a basicsix-sided enclosure and even when painted appear simple and plain withno design features. In addition, the thermal conductivity of the metalis high compared to plastic or other electrically non-conductivematerials making it difficult to insulate these enclosures for coldstorage applications.

When such metal enclosures include a drawer or multiple drawers, theweight of the enclosure is even higher. Heavy metal administration orstorage cabinets can be difficult to move and place in desired positionsand present an even more difficult handling situation when they arerequired to be stacked on one another.

RFID tracking containers are needed for various storage uses and thesizes required of the containers for such uses are different. Arequirement to manufacture different sizes of RFID tracking containers,one for each possible use, can be very expensive and inefficient.Similarly, having to use a shielded container that is much too large forthe particular application at hand is inefficient and can be expensive.It would be preferred if a modular approach to assembling an RF shieldedcontainer were available. In such a modular approach, various modules ofdifferent sizes and configurations would be available, all of which mayphysically fit together in various configurations as needed, and the RFshielding arrangements of these modules would be designed to fittogether to result in a fully RF shielded container for operating an RFtracking system within the container.

Hence, those of skill in the art have recognized a need for modularRF-shielded containers that may be assembled together to form variouscontainer shapes and sizes thereby obviating the expense of creatingcustom containers. Another need has been recognized by those of skill inthe art for reducing the cost of medical item containers and reducingtheir weight. Yet a further need has been recognized for using a lessexpensive material to build such containers, yet providing suchcontainers so that they nevertheless are RF shielded. Those of skill inthe art have also recognized a need for a more reliable configuration ofthe walls of a container so that when assembled to provide thecontainer, a better RF shield of the container is produced. Theinvention fulfills these needs and others.

SUMMARY OF THE INVENTION

The invention is directed to a lightweight, low cost, RF-shielded, andaesthetically pleasing alternative to the prior art metal enclosuresdescribed above. The invention provides a system of modular RF-shieldedplastic components that can be paired in various combinations to createRF-shielded drawers, containers, and enclosures of differing heights forthe purpose of tracking items of differing heights. Configurationsprovide both Faraday cages and tortuous path seals for preventing RFleakage.

In one aspect there is provided a medical article storage containerhaving an internal storage space, the storage container being shieldedfrom leaking radio-frequency (“RF”) energy out of and into the storagespace, the container formed with a plurality of interconnected walls,the container comprising a first wall located at a side of the storagespace, the first wall comprising a substrate formed of an electricallynon-conductive material, the first wall having a joining edge configuredto physically mate with another wall to form a joint seam between thetwo walls, the first wall also comprising an electrically conductivecomponent that is configured to be coextensive with the first wallsubstrate and extend to the joining edge of the first wall substrate atwhich location the electrically conductive component is exposed toelectrically connect with an electrically conductive component ofanother wall at the joint seam, the first wall also comprising a portionof a channel extending outwardly at the joining edge, the channelportion being as wide as the joining edge and having a shape including abend and configured to physically mate with a complementary portion of achannel of another wall that is joined with the first wall at the jointseam, and a second wall located at a side of the storage space, thesecond wall comprising a substrate that is formed of an electricallynon-conductive material, the second wall having a joining edge that isphysically mated with the joining edge of the first wall to form a jointseam between the two walls, the second wall also comprising anelectrically conductive component that is configured to be coextensivewith the second wall substrate and extend to the joining edge of thesecond wall substrate at which location the electrically conductivecomponent is exposed, the electrically conductive component of thesecond wall being electrically connected to the electrically conductivecomponent of the first wall at the joint seam, the second wall alsocomprising a portion of a channel extending outwardly at the joiningedge of the second wall, the channel portion of the second wall being aswide as the joining edge of the second wall and having a complementaryshape to the shape of the portion of the channel of the first wallincluding the bend, the second wall channel portion being physicallymated with the channel portion of the first wall to form an electricalchannel with a bend thereby providing a tortuous path seal at the jointseam to attenuate RF energy leaking out of and into the storage space,whereby the electrical connections of the first and second walls form apart of a Faraday cage around the storage space and the tortuous pathseal provides additional shielding against RF leakage.

In more detailed aspects, the electrically conductive components of boththe first and second walls are embedded into their respective walls andare configured to extend beyond the joining edges of their respectivewalls and be exposed to electrically mate with an electricallyconductive component of another wall at the joint seam thereby shieldingthe storage space from leaking RF energy. In another aspect, theelectrically conductive components of both the first and second wallsare embedded into their respective walls so that they form an outersurface of the wall and are configured to contact an electricallyconductive component of another wall at the joint seam thereby shieldingthe storage space from leaking RF energy. In yet a further aspect, theelectrically conductive components of both the first and second wallsare disposed over an outer surface of their respective walls and areconfigured to contact an electrically conductive component of anotherwall at the joint seam thereby shielding the storage space from leakingRF energy.

Other aspects include the channel forming a tortuous path seal by thefirst and second walls comprises a tortuous path having two bendsthereby increasing attenuation of energy RF energy out of an into thestorage space. In one case, the bend of the tortuous path seal is anangle of ninety degrees.

In yet a further aspect, the electrically-conductive component of thefirst wall comprises an electrically conductive metallic mesh embeddedin the first wall substrate, the mesh having openings of a size selectedin accordance with the frequency of the RF energy operating in thestorage space to provide a predetermined amount of attenuation of thatRF frequency energy at the first wall.

In other aspects, the first and second walls of the storage containerhave selectable sizes relative to each other wherein the first wall isused in a first storage container of a first size and the second wall isused in a second storage container of a second size that is differentfrom the first storage container, wherein the first and second storagecontainers are modular containers that are connected together at jointseams of the first walls of the first storage container being connectedto the second walls of the second storage container. A joint seam atwhich two modular containers are connected together comprises a ribcomprising an RF energy channel having a bend thereby providing atortuous path seal that attenuates RF energy leaking out of and into thestorage space formed by the interconnection of the modular containers.

In another aspect, the channel is configured with a size that attenuatesRF energy that is used for operation in the storage space, the channelfurther comprising electrically conductive shielding foam located at thebend in the channel, the electrically conductive shielding foamconfigured to attenuate RF energy in the channel, thereby providing anelectrical shield for the storage space. The channel further compriseselectrically conductive adhesive applied to the foam at a selectedposition in the channel, the electrically conductive adhesive holdingthe foam permanently in the selected position and contributing to theelectrical shield of the storage space. The channel is configured with asize that attenuates RF energy that is used for operation in the storagespace, the channel further comprising metal wool shielding locatedwithin the channel, the metal wool configured to attenuate RF energy inthe channel, thereby providing an electrical shield for the storagespace.

A further aspect is the substrates of the first and second walls areformed of a plastic having a relatively low coefficient of electricalconductivity whereby a lighter wall is provided.

In yet more detailed aspects, the first wall comprises an openingproviding access to the internal storage space, the first wall alsocomprising a door attached to an outer surface of the first wall mountedfor covering the opening at one position and uncovering the opening in asecond position, the door comprising electrically conductive material onits inner surface coextensive with the size of the door to electricallymate with the electrical component of the first wall to provide anelectric shield at and across the opening of the first wall, the firstwall further comprising a portion of a tortuous path seal located aboutthe opening of the first wall, and the door comprising a second portionof a tortuous path of a complementary shape to that of the portion onthe wall configured to accept the portion of the tortuous path of thedoor when the door is in the closed position such that the tortuous pathis completed when the door is in the closed position, whereby both aportion of a Faraday cage is provided by the electrical contact of thedoor with the electrical component of the opening and a tortuous pathseal if provided by the portions of the torturous seal being formed whenthe door is in the closed position.

Further, the tortuous path seal has a size selected to attenuate energyat an operating frequency in the storage space, and includes furthershielding through the use of electrical shield foam held in place withan electrically conductive adhesive at the bend.

In another aspect, the medical article storage container furthercomprises a drawer slidably located in the opening of the first wall andmovable into and out of the storage space, the drawer comprising thedoor over the opening by having a front wall that is larger than theopening in the first wall of the container and is located outside themedical article storage container but is movable to a closed position inrelation to the medical article container at which the front wall of thedrawer moves into contact with the first wall and covers the opening,wherein the drawer is formed of an electrically nonconductive material,wherein the drawer front wall includes an electrically conductivecomponent coexistent with the front wall of the drawer and configured atthe front wall of the drawer so that when the drawer is in the closedposition, the electrically conductive component of the front wall of thedrawer is placed into physical and electrical contact with theelectrically conductive component of the first wall at the opening ofthe drawer, wherein the front wall of the drawer further includes aportion of a tortuous path located about the edges of the front wall,and wherein the first wall of the medical article container includes asecond portion of a tortuous path located about the opening in the firstwall and having a shape that is complementary to the tortuous pathportion disposed about the edge of the front wall of the drawerconfigured so that when the drawer is closed, the two portions of thetortuous path mate and form a tortuous path seal shielding the storagespace from leakage into and out of the storage space of electricalenergy.

In a more detailed aspect, the tortuous path located about the frontwall of the drawer has a bend configured to attenuate electrical energy.

In yet a further detailed aspect, the medical article storage containerfurther comprises a first module having a false bottom under which arelocated an RFID reader and RFID probe and antenna, and comprising asecond module containing the internal storage space coupled to the firstmodule, the RFID reader and RFID probe and antenna configured to beusable with different sizes of second module attached to the firstmodule of the container. The second module is attached to the firstmodule at a joint seam, the container further comprising an RFIDshielding rib located over the joint seam and providing a Faraday cageshield and a tortuous path seal at the joint seam.

In accordance with method aspects of the invention, there is provided amethod of shielding an internal storage space of a medical articlestorage container from RF energy leakage out of and into the internalstorage space, comprising surrounding the internal storage space with aplurality of walls, the walls having a plastic substrate with anembedded electrically conductive component that is coextensive with thesubstrate, connecting together the coextensive electrically conductivecomponents of adjacent walls at joint seams, wherein each wall has ajoining edge configured to mate physically and electrically with ajoining edge of another wall to form a joint seam, thereby providingelectrically conducting walls located completely around the internalstorage space operating as a Faraday cage to attenuate RF energy andshield the internal storage area from leakage of RF energy, and formingan RF tortuous path seal at each joint seam through connecting togethera first portion of an RF tortuous path located at a first wall at thejoint seam with a complementary portion of an RF tortuous path locatedat a second wall at the same joint seam as the first and second wallsare mated together, wherein connecting together the first andcomplementary portions of the RF tortuous path provides a complete RFtortuous path configured to attenuate RF energy, thereby forming aFaraday cage around the entire internal storage area and formingtortuous path seals at the joint seams of the walls when connecting thewalls together, whereby the internal storage area is shielded againstthe leakage of RF energy out of the internal storage area and RF energyinto the storage area by both a Faraday cage and tortuous path seals.

The features and advantages of the invention will be more readilyunderstood from the following detailed description of embodiments thatshould be read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a prior art drawer that may bepositioned within a medical dispensing cabinet, showing the storage of aplurality of medical articles randomly positioned in the drawer, each ofthose articles having an integral RFID tag with the articles, andtherefore the tags on them, oriented randomly in the drawer;

FIG. 2 is a perspective view of a prior art medication dispensingcabinet (“ADC”) having five drawers, one of which is similar to theschematic view of FIG. 1, the cabinet also having an integral computerfor controlling access to the cabinet and for performing inventorytracking by periodically reading RFID tags placed on articles storedwithin the cabinet to identify stored medical articles, and forreporting the identified articles to a remote computer;

FIG. 3 is a block and flow diagram showing an embodiment in which anRFID reader transmits activating electro-magnetic (“EM”) energy into adrawer containing RFID tags with a single transmitting antenna, receivesthe data output from the activated RFID tags with a single receivingantenna, a computer controlling the transmission of activating energy,and receiving the data from the activated RFID tags for processing;

FIG. 4 is block and flow diagram similar to FIG. 3 showing an embodimentin which an RFID reader transmits activating EM energy into a drawercontaining RFID tags with two transmitting antennae, receives the dataoutput from the activated RFID tags with three receiving antennae, andas in FIG. 3, a computer controlling the transmission of activatingenergy and receiving the data from the activated RFID tags forprocessing;

FIG. 5 is an exploded view of a prior art ADC with the lower drawerremoved and the frame of the cabinet visible in the cavity where thedrawer was located, showing a representation of a Faraday cage to beformed within the frame at the cavity for the removed drawer, anRFID-enabling module, to be mounted within the cavity so that at leastthe antennae are within the Faraday cage, and the drawer havingpartitions to be slidably mounted within the representation of theFaraday cage, and also showing power and data connections for the modulewith the ADC;

FIG. 6A is a perspective front view of a container, also referred to asan enclosure, having an opening in which a slidable drawer may bemounted, the enclosure having a false bottom in which an RFID readercircuit and an associated antenna or antennae are mounted;

FIG. 6B presents a view of a drawer for use in the container of FIG. 6A,the drawer having front wall with a handle that are rigidly mounted tothe side walls of the drawer;

FIG. 6C presents a drawer similar to FIG. 6B except that the front wallof the drawer is hingedly mounted to the side walls, both of FIGS. 6Band 6C showing medical articles located in the drawers, each articlehaving an RFID tag attached;

FIGS. 7A, 7B, and 7C are schematic diagrams that depict the use ofmodular containers of plastic components of different sizes with astandard base having a false bottom with an RFID reader and an antennaor antennae for reading RFID tags, with FIG. 7A having the smallest sizeof an upper drawer module, FIG. 7B having a middle size of an upperdrawer module, and FIG. 7C having the largest size of an upper drawermodule, with FIG. 7D presenting an example schematic diagram of a drawerstoring a medical article that has an RFID tag attached;

FIGS. 8A and 8B depict an exploded perspective view of a top plasticcontainer and a bottom plastic container for insertion into anRF-enabled enclosure or drawer;

FIG. 9 depicts a partial cross-sectional view of an 80 gauge steel mesh(electrically conductive) sandwiched between an outer shell and an innershell both of which are formed of a plastic material that is RFtransparent (electrically nonconductive), thereby forming an RF shieldedwall material, the diagram also showing that the steel mesh comprises aportion that extends beyond the edge created by the plastic layers andis therefore exposed;

FIGS. 10A through 10C depict a forming process for embedding a metalmesh within a plastic shell by using a thermoform mold wherein a portionof the metallic mesh (electrically conductive component) extends beyondthe plastic components so that it is exposed;

FIG. 11 depicts another formed plastic wall in which is embedded anelectrically conductive component. In this embodiment, the metalcomponent is placed into an indent that exists in the side of theplastic wall and has been heated to embed that metal mesh into place inthe side of the plastic shell by using a thermoform mold. Theelectrically conductive metal component is therefore exposedcontinually;

FIG. 12 depicts a partial cross-sectional view of a plastic containermating with a plastic door, each having an exposed electricallyconductive component and each including mating ridges and channels forforming a tortuous path seal between the mating surfaces;

FIGS. 13A through 13D depict in schematic form and partialcross-sectional form, a top half and a bottom half of an enclosureconnected together by a U-shaped inner and outer rib, the halves of theenclosure both having an embedded electrically conductive component thatis coextensive with the plastic wall in which it is embedded and extendsbeyond the edge of the plastic wall so that the electrically conductivecomponent is exposed, and is bent into a configuration in which itcontacts the electrically conductive component of another wall tocomplete a Faraday cage around the enclosure;

FIG. 14 depicts a partial cross-sectional view of a one-piece inner andouter rib such as that shown in FIGS. 13b and 13D;

FIG. 15 depicts a partial cross-sectional view of a two-piece inner andouter rib connected together with exposed electrically conductive meshin contact to complete a Faraday cage and having ridges and channels forestablishing a tortuous path RF seal;

FIGS. 16 through 25 depict in schematic and partial cross-section formvarious embodiments of a first mating component attached to a secondmating component wherein a Faraday cage is completed and a tortuous pathRF seal is also formed by the particular physical and electrical matingtechnique. These figures also show the use of use of embedded metal meshcomponents in plastic walls, exposed electrically conductive components,the use of electrically conductive foam as an RF shield, the use ofconductive adhesive as an RF shield, and the use of a bundleelectrically conductive strands of metal wool as an RF shield;

FIG. 26 presents a schematic diagram of an enclosure having sixrectangular sides and showing the existence of twelve joint seams;

FIG. 27 shows in perspective view the front of an enclosure such as thatshown in FIG. 26 with an opening formed in its front wall;

FIG. 28 presents a front view of the enclosure of FIG. 27 with a portionof a tortuous path formed about the opening; and

FIG. 29 is a schematic diagram of an enclosure similar to that of FIG.26 showing the locations of tortuous path seals in dashed line at jointseams for shielding the seam from leakage of RF energy.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Detailed embodiments of the present invention are disclosed herein;however, it is to be understood that the disclosed embodiments aremerely exemplary and the invention may be embodied in various andalternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to employ thepresent invention.

Referring now in more detail to the exemplary drawings for purposes ofillustrating embodiments of the invention, wherein like referencenumerals designate corresponding or like elements among the severalviews, there is shown in FIG. 1 a schematic representation of a priorart device including a partial enclosure 20 in which a plurality ofmedical articles 22 are stored, each with a respective RFID tag 24 thathas a unique identification number. The partial enclosure may comprise adrawer having a front wall 26, a left side wall 28, a right side wall30, a rear wall 32, and a bottom 34. These articles are randomlydistributed in the drawer with the RFID tags facing in various andrandom directions.

As used in regard to the embodiments herein, “tag” is meant to refer toan RFID transponder. Such tags are well known and typically have acoupling element, such as an antenna, and an electronic microchip. Themicrochip includes data storage, also referred to as memory.

FIG. 2 depicts a representative prior art medical dispensing cabinet 40comprising a plurality of movable drawers 42. In this embodiment, thereare five drawers that slide outwardly from the cabinet so that access isprovided to the contents of the drawers. FIG. 1 is a schematic diagramof a representative drawer that may be positioned within the cabinet ofFIG. 2 for sliding outward to provide access to the drawer's contentsand for sliding inward into the cabinet to secure the drawer's contents.The cabinet also comprises an integral computer 44 that may be used tocontrol access to the drawers and to generate data concerning access andcontents of the drawers, and to communicate with other systems. In thisembodiment, the integral computer 44 includes a non-volatile memorydevice (not shown), such as a server, and generates data concerning thenumber and type of articles that are identified in the drawers throughan RFID tracking system. The integral computer 44 stores a database onthe memory device that correlates RFID tag identification numbers withmedical articles identified in the drawers. The database in oneembodiment includes the names of the patients for whom the identifiedmedical articles in the drawers have been prescribed, the prescribedmedications, their prescribed administration dates and times, theirexpiration dates (if any), the health care practitioner who prescribedthe medical article, as well as other information.

In a simpler system, the integral computer 44 may simply receive theunique identification numbers from the RFID tags on the stored medicalarticles and pass those identification numbers to an inventory controlcomputer that has access to a database for matching the RFID tagidentification numbers to medical article descriptions.

Such a cabinet 40 may be located at a nursing station on a particularfloor of a health care institution and may contain the prescriptions forthe patients of that floor. As prescriptions are prepared for thepatients of that floor, they are delivered and placed into the cabinet40. They are logged into the integral computer 44, which may notify thepharmacy of their receipt. A drawer may also contain non-prescriptionmedical supplies or articles for dispensing to the patients asdetermined by the nursing staff. At the appropriate time, a nurse wouldaccess the drawer in which the medical articles are stored through theuse of the computer 44, remove a particular patient's prescriptions andany needed non-prescription articles, and then close the drawer so thatit is secured. In order to access the cabinet, the nurse may need toprovide various information and may need a secure access code. Thedrawers 42 may be locked or unlocked as conditions require.

Systems that use RFID tags often employ an RFID reader in communicationwith one or more host computing systems that act as depositories tostore, process, and share data collected by the RFID reader. Turning nowto FIGS. 3 and 4, a prior art system and method 50 for tracking articlesare shown in which a drawer 20 of the cabinet 40 of FIG. 2 is monitoredto obtain data from RFID tags disposed with articles in that drawer. Asmentioned above, a robust field of EM energy needs to be established inthe storage site so that the RFID tags mounted to the various storedarticles will be activated, regardless of their orientation.

In FIGS. 3 and 4, the prior art tracking system 50 is shown foridentifying articles in an enclosure and comprises a transmitter 52 ofEM energy as part of an RFID reader. The transmitter 52 has a particularfrequency, such as 915 MHz, for transmitting EM energy into a drawer 20by means of a transmitting antenna 54. The transmitter 52 is configuredto transmit the necessary RFID EM energy and any necessary timing pulsesand data into the enclosure 20 in which the RFID tags are disposed. Inthis case, the enclosure is a drawer 20. The computer 44 of an RFIDreader 51 controls the EM transmitter 52 to cycle between a transmitperiod and a non-transmit, or off, period. During the transmit period,the transmitted EM energy at or above a threshold intensity levelsurrounds the RFID tags in the drawer thereby activating them. Thetransmitter 52 is then switched to the off period during which the RFIDtags respond with their respective stored data.

The embodiment of FIG. 3 comprises a single transmitting probe 54 and asingle receiving antenna 56 oriented in such a manner so as to optimallyread the data transmitted by the activated RFID tags located inside thedrawer 20. The single receiving antenna 56 is communicatively coupled tothe computer 44 of the reader 50 located on the outside of the drawer 20or on the inner bottom of the drawer. Other mounting locations arepossible. Coaxial cables 58 or other suitable signal links can be usedto couple the receiving antenna 56 to the computer 44. A wireless linkmay be used in a different embodiment. Although not shown in thefigures, those skilled in the art will recognize that various additionalcircuits and devices are used to separate the digital data from the RFenergy, for use by the computer. Such circuits and devices have not beenshown in FIGS. 3 and 4 to avoid unneeded complexity in the drawing.

The prior art device of FIG. 4 is similar to the prior art device ofFIG. 3 but instead uses two transmitting probes 60 and 62 and threereceiving antennae 64, 66, and 68. The configuration and the number oftransmitting probes and receiving antennae to be used for a system mayvary based at least in part on the size of the enclosure 20, thefrequency of operation, the relationship between the operation frequencyand the natural resonance frequency of the enclosure, and the expectednumber of RFID tags to be placed in it, so that all of the RFID tagsinside the enclosure can be reliably activated and read. The locationand number of RFID reader components can be dependent on the particularapplication. For example, fewer components may be required forenclosures having a relatively small size, while additional components,such as shown in FIG. 4, may be needed for larger enclosures. Althoughshown in block form in FIGS. 3 and 4, it should be recognized that eachreceiving antenna 56, 64, 66, and 68 of the system 50 may comprise asub-array in a different embodiment.

In FIG. 5 there is shown a medication cabinet 70 having its bottomdrawer 72 removed. In this case, the bottom drawer is formed of plasticand does not provide a Faraday cage for use in RFID-enabling the drawer.Also shown is an “RFID-enabling” drawer module 74 designed to establishand provide an environment in the removed drawer 72 in which itemshaving RFID tags placed in the drawer can be detected, identified, andtracked. The module in this embodiment includes probes and receivingantennae that must be mounted within a Faraday cage formed by or formedaround the drawer 72. Because the RFID-enabling module disclosed hereincan generate a robust EM field in a container regardless of the resonantfrequency of that container, retrofitting a drawer such as shown in FIG.5 becomes possible. The robust EM field created by the RFID-enablingmodule system is able to activate all RFID tags within the drawer sothat they may be read and the item to which they are attached can beidentified and tracked.

Because the present drawer 72 is formed of plastic, a Faraday cage mustbe formed around it. Accordingly, a Faraday cage, representedschematically in FIG. 5 as a box 76, is formed around the drawer. In theembodiment shown, it may comprise metallic walls that are mounted withinthe frame of the cabinet 70 to completely enclose the drawer once is itreinserted into the cabinet and closed. The metallic walls may be formedby various ways, one of which is to install metallic foil in the frameabout the drawer. The foil should be large enough to engage the front 78wall of the drawer to thereby complete the Faraday cage around thestorage area 104 of the drawer. The drawer front wall may also bepainted with metallic paint on the outside, sides, and inside the frontpanel to make contact with the foil in the frame of the cabinet andcomplete a Faraday cage that includes the front wall of the drawer. Asanother embodiment, metallic paint may be used within the frame of thecabinet to create the Faraday cage. Other means may also be used toconstruct or complete the Faraday cage to surround the container inwhich items are being identified and tracked.

In an embodiment where the drawer is metallic and itself forms a Faradaycage, the antennae of the module 74 must be mounted to be within thecage to communicate with the field and RFID transmissions within thecage. In some cases, the module is placed above the drawer and in othercases, it may be placed below the drawer, depending on the configurationof the cabinet and the drawer. Additionally more than one drawer in acabinet can be RFID-enabled, according to aspects of the invention.

As mentioned, the module 74 can be mounted above the drawer toRFID-enable the drawer. In the embodiment shown in FIG. 5, the modulehas two probes 82 that protrude above its surface by a certain distance.In this case, they are centered on the module. To accommodate thoseantennae, a notch 80 has been formed in the back of the drawer so thatthe drawer back will not damage the probe antennae when the drawer ispulled to the open position and pushed to the closed position. Themodule 74 may be mounted within the Faraday cage by standoffs and screwsinto the ceiling of the frame around the drawer. Other mountingtechniques are possible.

FIG. 5 also shows connection of the module 74 to a power source 86 andto data communications 88 with a local computer 84. In the embodimentwhere the module 74 is connected to an Ethernet (not shown), the powermay be provided entirely by the Ethernet connection (Power over Ethernetor “PoE”). Additionally, the local computer 84 may be programmed toprocess RFID data of identified and tracked items by the module 74 inthe RFID-enabled drawers 72 of the cabinet 70, and may also beprogrammed to create a data base of those items and the RFID dataassociated with them. The processed RFID data and the data base may becommunicated to a central server and its data base, or may becommunicated elsewhere or to additional locations. The local computer 84would also contain a data base of the installed hardware, the hardwareaddress correlated to which drawer, and other various data base items.Since construction of such a program and data base are well within theskill of those in the art, no further detail is provided here.

In keeping with the invention, and referring to FIGS. 6A and 6B, anRF-enabled drawer 100 is used to identify and track medical articleswith an RFID tag system. The drawer 100 functions similarly to astandard mechanical drawer in that a handle 102 or knob is used to openthe drawer revealing the storage area 104. In this embodiment, thedrawer bottom 106, left side 108, right side 107, and back side 109 arefabricated from a non-metallic material that is transparent to RFenergy, such as a plastic. The drawer front wall or door 110 is formedfrom a metallic or RF-shielded material in order to form the RF-shieldedfront door of the drawer enclosure 112 and complete a Faraday cagearound the storage area of the drawer.

The drawer enclosure 112 (FIG. 6A), which is formed of a metallicmaterial, includes a false bottom 114 in which the RFID reader 116 andantennas 118 are mounted, and above which the storage area 104 of thedrawer 100 slides. The RFID tags 124 attached to the items 122 (e.g.,medical articles) stored in the drawer are identified by the modulatedRF energy transmitted by the antennas 118 mounted in the false bottom114. The area under the false bottom, which exists to protect the RFIDreader and antennas, and the area surrounding the drawer storage area104, together make up the RF-enabled enclosure. In this embodiment, thedrawer enclosure 112 is formed of a metallic material, and together withthe door 110, form a Faraday cage around the storage area of the drawer.In other words, the drawer enclosure 112 can be formed from a metallicmaterial, while the drawer 100 itself is formed from a non-metallicmaterial that is transparent to RF energy, except for the front wall.The front wall of the drawer, the door 110, is formed of a metallic orRF-shielded material in order to complete the Faraday cage.

In another embodiment shown in FIG. 6C, another embodiment of anRF-enabled drawer 130 is shown for use in tracking medical articles inits storage area 104 and is similar to the RF-enabled drawer 100 of FIG.6B. The difference is that the front wall comprises a hinged door 132that is formed of a metallic material and attached to the storage area104. The hinged door 132 opens downward, or upward, on a hinge 134, orsideways on one hinge, or two doors opening opposite one another onhinges (i.e., French doors). The door 132 is formed of a metallic orRF-shielded material and it forms the front cover of the drawerenclosure 130 as shown in FIG. 6C.

In another embodiment, as shown in the schematic front view diagrams ofFIGS. 7A, 7B, and 7C, RF-enabled enclosures 140A, 140B, and 140C areused to track medical articles. These enclosures comprise the samemodular lower container 144 that includes a false bottom in which islocated an RFID reader 116 and probes and antennae 118, as required.However, the upper modular containers in these figures are differentsizes. In particular, FIG. 7A has the smallest upper modular container,FIG. 7B has a middle size upper modular container, and FIG. 7C has thelargest upper modular container. In one embodiment, the height of thedrawer in FIG. 7A was two inches (5.08 cm), the height of the drawer inFIG. 7B was three inches (7.62 cm), and the height of the drawer in FIG.7C was four inches (10.16 cm).

In each case of FIGS. 7A, 7B, and 7C, the enclosure is accessed by wayof a door 141 that opens downward or upward on a hinge 142 or sidewayson one hinge or two doors opening opposite one another on hinges (i.e.,French doors). Opening the door of this enclosure reveals a space orvolume into which non-metallic trays 147 (FIG. 7D), bins, boxes, etc.,can be placed for identification of the RFID tagged 145 items 146contained therein. The hinges are shown schematically in the figures bycircles at the lower left and right corners of the doors, forillustration only. The coupling location of the upper module 140A to thelower module 144 in FIG. 7A, for example, is schematically shown bysemi-circles with the open portion of the semi-circle facing downward.This schematic indicator is also used for illustration purposes only andit not indicative of or restricted to any particular joint type orconnecting mechanism.

The enclosures shown in FIGS. 7A, 7B, and 7C all include a false bottom144 which is of the same height as the false bottom 114 in theRF-enabled drawer enclosure 112 of FIG. 6A. The RFID tags attached tomedical articles, such as RFID tag 145 attached to medical article 146,stored in trays 147, bins, boxes, etc., located within the upper modularcontainers are identified by the modulated RF energy transmitted byantennas 148 mounted in the false bottom 144. The area under the falsebottom, which exists to protect the reader and antennas, and the area inwhich the trays, bins, boxes, etc., are placed, together make up theRF-enabled enclosure. In this embodiment, the false bottom 144 isidentical in size for each top portion of the RF-enabled enclosure 140A,140B, and 140C. The height of the enclosures 140A, 140B, and 140C differin order to accommodate different sized items 146 placed in the trays,boxes, bins 147. The interface 149 between the enclosures 140A, 140B,140C and the false bottom 144 is designed to incorporate tortuous pathfeatures as described below. All of these RF-enabled components togetherhelp to form a Faraday cage.

In one embodiment, as shown in FIG. 8A, a top plastic container 150 anda bottom plastic container 152 form an enclosure when paired together.The top and bottom containers 150, 152, are stacked together forinsertion through opening 153 and placement inside of an RF-enabled(shielded) drawer 154.

The RF-shielded plastic bottom container 152 is formed of an inner shell156 and an outer shell 158 formed of a plastic material. As shown inFIG. 8B, the outer shell 158 is RF-shielded by incorporating a metalscreen or metal mesh 160 onto or into the plastic during the formingprocess. The inner shell 156 is not shielded, and is composed of an RFtransparent material such as plastic, and serves as the false bottom 162of the RF-enabled drawer 154. The plastic bottom container 152 alsoincludes shielded torturous path features 164, around the top perimeter166 for attachment to the top plastic container 150. The plastic bottomcontainer 152 of the drawer enclosure also includes an opening or cutout 170 in the front of the component to provide drawer access.

The plastic top container 150 of the RF-shielded plastic drawerenclosure 154 in FIG. 8A can be a single or double shell plasticcomponent and includes at least one shell that is RF-shielded during theforming process such as shown in FIG. 8B. The plastic top container 150also includes shielded torturous path features 164 (not shown), aroundthe bottom perimeter 168 for attachment to the plastic bottom container152. The plastic top container 150 includes an opening or cut out 172 inthe front of the component to provide drawer access.

Both top and bottom RF-shielded plastic containers 150 and 152 includefeatures around the perimeter of the opening or cut out 170 and 172 thatfacilitate the RF sealing of a drawer face plate (not shown) to thedrawer enclosure 154. One bottom RF-shielded plastic container 152 canbe fabricated to mate with several top RF-shielded plastic containers toform RF drawer enclosures of differing heights. For example, anRF-enabled automated dispensing cabinet might require three differentdrawer heights for storing RF-tagged items. The same bottom RF-shieldedplastic container can be used for all three “different heights” topRF-shielded plastic containers. The top RF-shielded plastic container150 defines the height of the drawer 154.

The RF-shielded plastic components described above are formed by aprocess whereby the RF-shielding material is incorporated onto or intothe plastic during the forming process. In one embodiment, as shown inFIG. 9, the shielding material is an 80 gauge steel mesh 180 that isattached to the surface of either or both of an outer shell 182 and aninner shell 184. In one embodiment, the 80 gauge metal mesh is attachedwith adhesive between the inner and outer shells, i.e., sandwichedbetween the plastic shells to form a shielding wall for use in a Faradaycage. Alternatively, a conductive epoxy can be used to attach andsandwich the metal mesh 180 between the outer and inner shells 182, 184.In this embodiment, the mesh 180 is coextensive with the plastic layers(outer and inner shells 182 and 184) and has a portion 181 that extendsbeyond the edge 183 formed by the plastic layers. As is shown in otherfigures below, this extended portion is used to make connection withelectrically conductive components of other walls or features of otherplastic devices.

As is used herein, coextensive means that the electrically conductivemesh, or layer, or paint, or other material has a size that is at leastas large as the plastic component into which or on which it is embedded.Its purpose is to provide a Faraday cage around the storage area formedby plastic walls. In the case of FIG. 9, the metal mesh 180 is not onlycoextensive with the plastic shells, it is larger than the shells sothat it can be manipulated into electrical contact with the electricallyconductive material of other walls, drawers, doors, or other componentsof a plastic enclosure.

Different RF energy ranges will require appropriate gauge metal mesh toform the Faraday cage. For example, the metal mesh can range from 60gauge to 120 gauge depending on the level of RF energy used with theRFID tags.

In one embodiment, as shown in FIGS. 10A through 10C, the electricallyconductive metal mesh 190 is procured embedded in a polyester shell 192,or similar plastic material, and molded into the enclosure plastic. Inthis embodiment, the metal mesh 190 is procured or purchased with themetal mesh being embedded in the polyester (plastic shell) 192, and thenthe plastic shell 192 is molded along with a second plastic shell 194 bythermoforming on thermoform mold 196 as shown in FIG. 10B. In thisembodiment, as in FIG. 9, the metal mesh 190 is not only coextensivewith the plastic shell, but it is also longer than the shell and extendspast an edge of the plastic shell for use in making electrical contactwith electrically conductive material of other walls or parts of anenclosure. Further referring to FIG. 10B, the mold 196 is shownthermoforming the plastic shell 192 having an electrically-conductivemesh 190 embedded in it and the second plastic shell 194 being molded.

The end product, as shown in FIG. 10C, is the plastic shell 192 and thesecond plastic shell 194 taking the shape of the thermoform mold 196,with the metal mesh 190 also conforming to the thermoform mold. Theembedded metal mesh 190 into plastic shell 192 results in an RF-enabledFaraday cage suitable for forming the containers, drawers, plasticboxes, plastic shells, and other plastic components described herein. Inanother embodiment, the metal mesh is procured embedded in polyester, orsimilar plastic material, and then molded separately from the enclosureplastic. Then the two molded components nest together in the finalassembly of the RF-enabled enclosure.

Referring now to FIG. 11, a different type of wall is shown. In thisembodiment, the plastic material 194 included an indent 195 on itsunderside. An electrically conductive metal mesh having a thicknessequal or less than the depth of the indent was inserted into thatindent. The metal mesh is held in place in the indent with adhesive, orthermoforming or by other means. Because of the depth of the indent andthe equal or smaller thickness of the metal mesh, the underside of theplastic with the metal mesh is smooth.

In one embodiment of the invention, a top plastic enclosure and a bottomplastic enclosure are mated together similarly to those shown in FIG.8A. The plastic enclosures are shielded with either an embedded metalmesh or a conductive metal coating in order to form a Faraday cage.Importantly, there is a risk of RF energy leakage at the mating surfaceswhere the two halves are joined together. The same risk applies to adoor that mates with an opening in a container or drawer. The inventorhas found that positioning a tortuous path at this positionsubstantially reduces the risk of RF energy leaking out of thecontainer. A tortuous path is one that is not straight but instead hasat least one bends. Each bend in the tortuous path causes attenuation inRF energy traversing the path. Whether by reflections or resistance, theenergy is attenuated and leakage of RF energy out of the container isreduced. In order to ensure a tortuous path seal, the mating surfacesinclude both foam seals at the mating surfaces and a conductive epoxy inorder to reduce the likelihood of RF energy leakage. Further, in oneembodiment, a plastic door is connected to either the top or bottomdrawers and is hinged to open and close for access into to the drawer.The plastic door includes an embedded mesh or conductive coating inorder to form a Faraday cage with the RF-shielded top and bottom plasticdrawer or enclosure. In order to eliminate or reduce the likelihood ofRF energy leakage through the seal existing between the door and theenclosure, a foam seal and a conductive epoxy are positioned between thedoor and the drawer.

Foam RF shields, also referred to as seals are available from Chomerics,77 Dragon Street, Woburn, Mass. 018898. For example, the Soft-Shield®4850 UL 94 V-O, multiplanar EMI gaskets and the plated fabric wrappedfoam EMI shielding gaskets have been found to be useful. Certain foamshields have an adhesive mounted at one side. To use the adhesive formounting the foam at a selected location, a removable tape strip ispeeled away from the adhesive.

As disclosed herein there are numerous embodiments of RF-shieldedenclosures in which there are mating surfaces that may be exposed andsusceptible to RF energy leakage, thus requiring a torturous path seal.In one embodiment, as shown in FIG. 11, a plastic enclosure 200 iscomprised of a plastic material embedded with a metal mesh 202 orconductive metal coating as described above. A plastic door 204 havingan embedded metal mesh 202 or conductive coating mates with and closesan opening in the RF-enabled plastic enclosure or container. In thisembodiment, several foam seals 206 are incorporated into channels 208,and between ridges 210 on the inner surface 212 of the door 204. Thedoor ridges 210 and channels 208 mate with complementary ridges 214 andchannels 216 of the plastic enclosure 200. Further, in order to ensure atortuous path door seal, a conductive epoxy 218 is applied between thedoor inner surface 212 and the ridges 210, 214 and channels 208, 216.This will reduce the likelihood or eliminate any RF energy leakagearound the mating surfaces between the door 204 and the plasticenclosure 200.

In another embodiment, as shown in FIG. 12, a tortuous path seal isformed between a plastic or metal drawer 220 and a thermoform plastic222 or metal container. In this embodiment, a thermoform RF-enabledplastic 222, or a metal formed container, receives a RF-enabled plasticdrawer 220, or a drawer formed from a metallic structure. Importantly,the mating surfaces between the drawer and the container require atortuous path seal. The drawer includes ridges 224 and channels 226 onthe inner surface 228 of the drawer, with a conductive epoxy 230attaching the ridges 224 and channels 226 to the inner drawer surface228. A foam seal 232 is positioned in the channels 226. Similarly, thecontainer 222 includes ridges 234 and channels 236 that are mattinglyconfigured to mesh with the ridges 224 and channels 226 of the drawer220. The ridges 224, 234 and channels 226, 236 of the drawer 220 andcontainer 222 are attached by the conductive epoxy 230. If the drawer220 and container 222 are formed of a plastic material, it will beembedded with a metal mesh screen 238 or coated with a conductive layerin order to form a Faraday cage.

In another embodiment, as shown in FIGS. 13A through 13D, a modularplastic RF-shielded enclosure 240 has an upper half 242 and a lower half244 of plastic RF-shielded material joined together to form a tortuouspath connection between the components. In this embodiment, both plasticsections include embedded metal mesh screens 246 or exposed screenmaterial, or an embedded conductive metal layer, for low resistanceconnections between the sections, and the formation of a Faraday cagewithin the enclosure. Importantly, where the two halves of the plasticshielded enclosure are joined, a tortuous path seal is required in orderto reduce the likelihood or eliminate RF energy leakage.

In this embodiment, the top half 242 of the plastic RF-shieldedenclosure includes an offset mating surface 248 which mates with asecond mating surface 250 of the lower half 244 of the RF-shieldedenclosure 240. In order to connect the upper half of the enclosure tothe lower half of the enclosure and to form the tortuous path seal, aU-shaped inner rib 252 is matingly attached to a U-shaped outer rib 254.The inner and outer ribs 252, 254 are formed from plastic and areRF-shielded with the embedded metal mesh screen 246. As shown in FIG.13D, the inner and outer ribs 252, 254 connect the upper half 242 to thelower half 244 along the offset mating surface 248 and the second matingsurface 250. In addition, the U-shaped inner rib 252 provides a solidbase to which drawer rails 256 are mounted while the U-shaped outer rib254 provides a base by including threaded inserts 258 to which screwscan be used to attach the outer rib to a cabinet, as more clearly shownin FIG. 13C. A metal fabric or foam, or a conductive epoxy 260 ispositioned between the first and second mating surfaces in order tofurther reduce the likelihood or eliminate RF-energy leakage at themating surfaces. Additionally, the embedded metal mesh screens 246 ofthe upper and lower halves 242 and 244 have extended beyond the edge ofthe plastic substrates of the halves and have been bent around betweenthe two pieces 242 and 244 to touch and create an electrical connection.Also, the electrically conductive epoxy adhesive 260 will alsocontribute to completing that electrical connection.

The inner and outer ribs shown in FIGS. 13A through 13D can be formed ofa one-piece construction 262 as shown in FIG. 14, or a two-piececonstruction 264 as shown in FIG. 15. Each of the embodiments shown inFIGS. 14 and 15 include embedded metal mesh or screen or embeddedconductive layers in order to form a Faraday cage, as well as reducingthe likelihood or eliminating RF energy leakage by forming a tortuouspath seal between mating surfaces. Either embodiment also can be coatedwith a conductive material. With respect to FIG. 15, the inner and outerribs are formed of a two-piece construction. For example, the outer rib254 is joined to the inner rib 252 by a series of mating channels 266 inthe outer rib 254 and projections 268 in the inner rib with a conductiveepoxy 260 used as the adhesive to join the two rib sections.

Numerous other embodiments exist for forming a tortuous path sealbetween multiple parts for forming an effective and operable Faradaycage from shielded plastic enclosures or components. For example, asshown in FIGS. 16-25, various enclosures, containers or drawers havemating surfaces that require a tortuous path seal between the matingsurfaces to avoid RF leakage. Each embodiment includes a first matingcomponent 270 and a second mating component 272 having surfaces thatmate together where the potential for RF energy leakage can occur. Inorder to reduce the likelihood or eliminate RF energy leakage betweenthe mating components 270 and 272, each of the components is embeddedwith a metal mesh screen 274 either entirely within the plastic of thewall or embedded so that it forms an outside wall surface. Some of theembodiments have used the metal mesh 274 that extends past the matingsurface to wrap around the bends and into contact with extended externalmetal mesh in the opposing piece. Further, in some embodiments, aconductive epoxy 276 is positioned between the first mating component270 and the second mating component 272 Likewise, a foam or conductivefoam 278 can be placed between the first and second mating components inorder to form a tortuous path seal between the mating surfaces.

Referring to FIGS. 16-19, a layer of metal mesh is a surface of a wallthat contacts the metal mesh of the wall with which it joins to form atortuous path seal. In FIGS. 20-21, the metal mesh was fully embedded inthe plastic but portions of mesh extending beyond the plastic edge havebeen bent around into the joint with the other piece and other piece'smesh to make electrical contact between the two. FIG. 22 shows atortuous path seal where the electrical contact between the embeddedmetal meshes of the two parts are joined by a screw that comes incontact with both meshes and provides an electric contact between them.FIG. 23 has internally embedded metal mesh in the two parts that is bentaround their contact point so that the mesh of each piece is in contact.The figure also shows the use of electrically conductive epoxy adhesive276 and electrically conductive foam 278 to contribute to the RFshielding.

In FIG. 24, the metal mesh of the piece at the left extends beyond theedge of the plastic substrate 272 and that mesh has been bent around theareas where the two pieces join. Also, the metal mesh of the piece atthe right is an external layer on the plastic that makes electricalcontact with mesh of the piece on the left. Electrically conductiveepoxy and foam are used in this embodiment also. In FIG. 25,electrically conductive metal mesh 274 is shown in dashed lines for thepurpose of clarity in the drawing. In actuality, it is a layer on theplastic substrates of both pieces and is on the side that faces theother piece so that electric contact is made for the purpose of forminga Faraday cage as discussed above. FIG. 25 also shows the use of metalwool 280 positioned between the pieces to provide increased RFshielding.

Turning now to FIG. 26, an enclosure 300 having a generally rectangularshape is shown. It can be seen that the enclosure 300 has six sideswhich are a front, a back, a top, a bottom, and two sides. Each of thesesides is connected to four other sides. At each of these connection is ajoint seam. There are therefore twelve joint seams. These are numerals302, 304, 306, 308, 310, 312, 314, 316, 318, 320, 322, and 324. At eachof these joint seams, the leakage of RF energy into and out of the spacewithin the enclosure can occur.

Referring briefly to FIG. 27, an abbreviated front perspective view ofan enclosure 330 having an opening 332 in the front is shown. Theenclosure is formed of six plastic walls, each of which comprises anelectrically conductive component that is extensive with the wall. Allthe electrically conductive components are electrically connected witheach other through one or more joining techniques described above andthus a Faraday cage has been formed. However this Faraday cage has theopening 332 through which RF leakage could occur.

This opening 332 may be used for a sliding drawer or for other purposes.The opening is meant to be covered and at the area of coverage, RFleakage can occur. FIG. 12 presents a means of establishing a tortuouspath seal around the opening. In FIG. 28, a front perspective view of aportion of a tortuous path 331 is shown. There are dual rows ofinterspaced ridges 336 and channels 350. In order to preserve theclarity of the illustration, neither every ridge nor every channel hasbeen indicated with a drawing numeral. When this portion of a tortuouspath is combined with the portion of a tortuous path contained on theinside surface of the drawer wall 220 shown in FIG. 12, a tortuous pathseal will be formed around the opening. Because all of the componentsshown in FIG. 12, including the ridges 336, channels 350, and foam areelectrically conductive, a full Faraday cage will be formed when drawerwall 220 is pushed against the opening 332. The entire enclosure will bein electrical contact. Also, a tortuous path seal will also be formedaround the opening 332 by means of moving the drawer wall portion of atortuous path into contact with the complementary tortuous path portionof the opening 332.

FIG. 29 schematically shows the locations of tortuous path seals 332,334, 336, 338, 340, 342, and 344 of an enclosure at the seams wherewalls are joined together. Additionally, a portion of a tortuous pathseal 340 is shown around the opening 332 on the front wall. Whencombined with a door or drawer wall having a complementary tortuouspath, a torturous path seal will then be formed as exist at other jointseams in the FIG. 332, 334, 336, 338, 340, 342).

The RF shielding includes thermoformed, pressure formed, etc. plasticcomponents that include features providing a torturous path designnecessary to ensure RF isolation. Torturous path features areincorporated into the plastic structures where the components are pairedto create an RF-shielded enclosure with the RF isolation required toensure that each enclosure provides not only a “Faraday cage” but also atortuous path seal to result in the necessary isolation required toensure that RFID tags in one enclosure are not read by the reader in anadjacent enclosure. Furthermore, one implementation of the RF-shieldedplastic enclosure is composed of a small enclosure within a largerenclosure, where the small enclosure is RF-shielded by RF-shieldingmaterial positioned between the two enclosures. This implementation ofthe invention provides a means of easily insulating the smallerenclosure for those applications that require a cold storage area.

By incorporating the RF-shielding material into the plastic during theforming process and by designing the torturous path features into theplastic component shape, the invention provides a low cost, light weightalternative to metal enclosures. By providing a modular system wherebycomponents can be paired to create drawers and enclosures of differingsizes, the invention eliminates the requirement for custom metal drawersand enclosures to meet the specific requirements of each trackingapplication.

Excluding upright refrigerated enclosures with side swinging doors, thetwo basic forms of small enclosures used to track medication using RFIDtechnology are drawers and enclosures. In one aspect, RF-enabled drawersare used that are similar to a standard mechanical drawer in that ahandle or knob is used to open the drawer thereby revealing a storagearea. The drawer bottom, left side, right side, and back side arefabricated from a non-metallic material that is transparent to RFenergy. The front of the drawer is made of a metallic or RF-shieldingmaterial as it forms the shielded front cover of the drawer enclosure.The drawer enclosure includes a false bottom in which the RFID readerand antennas are mounted, and above which the storage area of the drawerslides. The RFID tags attached to the items stored in the drawer areidentified by the modulated RF energy transmitted by antennas mounted inthe false bottom. The area under the false bottom, which exists toprotect the reader and antennas, and the area surrounding the drawerstorage area together make up the RF-enabled enclosure.

In one aspect, RF-shielded plastic components or shells form anenclosure when paired together. For example, in the case of theRF-enabled drawer of a fixed width and depth, one RF-shielded plasticbottom half is formed having an inner shell and an outer shell. Theouter shell is RF-shielded by incorporating a metal screen or metal meshonto or into the plastic during the forming process. The inner shell isnot shielded, and is composed of an RF transparent material such asplastic, and serves as the false bottom of the RF-enabled drawer. Theplastic bottom half also includes shielded torturous path features,around the top perimeter for attachment to the top half of the RFenclosure. The bottom half of the drawer enclosure may also include anopening or cut out in the front of the component to provide draweraccess. The top half of the RF-shielded plastic drawer enclosure can bea single or double shell plastic component and includes at least oneshell that is RF-shielded during the forming process. The plastic tophalf also includes shielded torturous path features, around the topperimeter for attachment to the bottom half of the RF enclosure. The tophalf of the drawer enclosure includes an opening or cut out in the frontof the component to provide drawer access. Both top and bottomRF-shielded plastic halves or components include features around theperimeter of the drawer opening that facilitate the RF sealing of thedrawer face plate to the drawer enclosure. One bottom RF-shieldedplastic component can be fabricated to mate with several top RF-shieldedplastic components to form RF drawer enclosures of differing heights.For example, an RF-enabled automated dispensing cabinet might requirethree different drawer heights for storing RF tagged items. The samebottom RF-shielded plastic component can be used for all three“different heights” drawer enclosures. The top RF-shielded plasticcomponent defines the height of the drawer.

The invention provides a system of modular RF-shielded plasticcomponents. The components are paired in various combinations to producethe enclosures necessary to track RFID tagged items in drawers andenclosures. The plastic components are shielded with a metal mesh thathas been incorporated into the plastic structure during the formingprocess. The plastic components include features around the perimeterthat facilitate the mechanical attachment of the two enclosure halves(i.e., top and bottom). The mechanical features also include thetorturous path design required to isolate the enclosure for the purposeof containing the RF energy in the enclosure.

Another aspect includes the modular design of the shielded plasticcomponents. The shielded plastic components are designed to mate inpairs to create enclosures or drawers of varying sizes. Since the RFIDreader and read antennas are positioned under a false bottom in the baseof both enclosures and drawers, one shielded plastic half or base can bedesigned for use in both drawers and enclosures of a specific width.

As used herein for convenience, the well-known Faraday cage or Faradayshield or Faraday cavity is an enclosure formed by electricallyconductive material. A metal mesh of such material is one embodiment.Such an enclosure prevents RF energy generated inside the Faraday cagefrom leaking out and blocks out external static electric fields. AFaraday cage is not limited to square or rectangular sides and may takeother forms.

As used herein, “embedded” means fixing an object firmly in a mass. Inaccordance with the usage herein, an object that is fully surrounded bythe mass is embedded and an object that is only partially surrounded bythe mass is embedded.

As used herein, “substrate” is used in a broad sense. Not only can thesubstrate have another component mounted to its exterior surface, it isalso meant to include embedding another component fully within itsinterior, as well as embedding a portion of a component in its interiorand mounting another portion of that same component to the substrate'sexterior.

As used herein, “wool,” “metal wool,” “wire wool,”“electrically-conductive wool,” and “steel wool” refer to a bundle ofelectrically-conductive strands, and may be used interchangeably. Thestrands, which may also be described as filaments or fibers, maycomprise fine carbon steel strands, low-grade carbon steel wire,stainless steel strands, aluminum strands, or otherelectrically-conductive material that are bunched into a fuzzy mass thatresembles wool. The strands may vary in softness depending on their sizeand the application. The strands are configured to conduct electricitythroughout the bundle, including transversely and longitudinally. Theremay or may not be backing material on either side or on one side of thebundle of electrically-conductive wool depending on the application.

A tortuous path seal described herein is also referred to as a tortuousseal and sometimes as a labyrinth seal.

Unless the context requires otherwise, throughout the specification andclaims that follow, the word “comprise” and variations thereof, such as,“comprises” and “comprising,” are to be construed in an open, inclusivesense, which is as “including, but not limited to.”

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A medical article storage container having aninternal storage space, the storage container being shielded fromleaking radio-frequency (“RF”) energy out of and into the storage space,the container formed with a plurality of interconnected walls, thecontainer comprising: a first wall located at a side of the storagespace, the first wall comprising a substrate formed of an electricallynon-conductive material, the first wall having a joining edge configuredto physically mate with another wall to form a joint seam between thetwo walls, the joining edge having a width, the first wall alsocomprising an electrically conductive component that is configured to becoextensive with the first wall substrate and extend to the joining edgeof the first wall substrate at which location the electricallyconductive component is exposed to electrically connect with anelectrically conductive component of another wall at the joint seam, thefirst wall also comprising a portion of a channel extending outwardly atthe joining edge, the channel portion being as wide as the joining edgeand having a shape including a bend and configured to physically matewith a complementary portion of a channel of another wall that is joinedwith the first wall at the joint seam; and a second wall located at aside of the storage space, the second wall comprising a substrate thatis formed of an electrically non-conductive material, the second wallhaving a joining edge that is physically mated with the joining edge ofthe first wall to form a joint seam between the two walls, the joiningedge having a width, the second wall also comprising an electricallyconductive component that is configured to be coextensive with thesecond wall substrate and extend to the joining edge of the second wallsubstrate at which location the electrically conductive component isexposed, the electrically conductive component of the second wall beingelectrically connected to the electrically conductive component of thefirst wall at the joint seam, the second wall also comprising a portionof a channel extending outwardly at the joining edge of the second wall,the channel portion of the second wall being as wide as the joining edgeof the second wall and having a complementary shape to the shape of theportion of the channel of the first wall including the bend, the secondwall channel portion being physically mated with the channel portion ofthe first wall to form an electrical channel with a bend therebyproviding a tortuous path seal at the joint seam to attenuate RF energyleaking out of and into the storage space; whereby the electricalconnections of the first and second walls form a part of a Faraday cagearound the storage space and the tortuous path seal provides furthershielding from RF leakage.
 2. The medical article storage container ofclaim 1 wherein the electrically conductive components of both the firstand second walls are embedded into the substrate of their respectivewalls and are configured to extend beyond the joining edge of theirrespective walls and be exposed to electrically mate with anelectrically conductive component of another wall at the joint seamthereby shielding the storage space from leaking RF energy.
 3. Themedical article storage container of claim 1 wherein the electricallyconductive components of both the first and second walls are embeddedinto the substrate of their respective walls so that they form an outersurface of the wall which is configured to contact an electricallyconductive component of another wall at the joint seam thereby shieldingthe storage space from leaking RF energy.
 4. The medical article storagecontainer of claim 1 wherein the electrically conductive components ofboth the first and second walls are disposed over an outer surface ofthe substrate of their respective walls and are configured to contact anelectrically conductive component of another wall at the joint seamthereby shielding the storage space from leaking RF energy.
 5. Themedical article storage container of claim 1 wherein the channel forminga tortuous path seal by the first and second walls comprises a tortuouspath having two bends thereby increasing attenuation of leaking RFenergy.
 6. The medical article storage container of claim 1 wherein thebend of the tortuous path seal is an angle of ninety degrees.
 7. Themedical article storage container of claim 1 wherein theelectrically-conductive component of the first wall comprises anelectrically conductive metallic mesh embedded in the first wallsubstrate, the mesh having openings of a size selected in accordancewith the frequency of the RF energy operating in the storage space toprovide a predetermined amount of attenuation of the RF energy at theoperating frequency.
 8. The medical article storage container of claim 1wherein the first and second walls have selectable sizes relative toeach other wherein the first wall is used in a first storage containerof a first size and the second wall is used in a second storagecontainer of a second size that is different from the first storagecontainer, wherein the first and second storage containers are modularcontainers that are connected together at joint seams of the first wallsof the first storage container being connected to the second walls ofthe second storage container.
 9. The medical article storage containerof claim 8 wherein a joint seam at which two modular containers areconnected together comprises a rib disposed over the joint seam, the ribcomprising an RF energy channel having a bend thereby providing atortuous path seal that attenuates RF energy leaking out of and into thestorage space.
 10. The medical article storage container of claim 1wherein the channel is configured with a size that attenuates RF energyused for operation in the storage space, the channel further comprisingelectrically conductive shielding foam located at the bend in thechannel, the electrically conductive shielding foam configured toattenuate RF energy in the channel, thereby providing an electricalshield for the storage space.
 11. The medical article storage containerof claim 10 wherein the channel further comprises electricallyconductive adhesive applied to the foam at a selected position in thechannel, the electrically conductive adhesive holding the foampermanently in the selected position and contributing to the electricalshield of the storage space.
 12. The medical article storage containerof claim 1 wherein the channel is configured with a size that attenuatesRF energy that is used for operation in the storage space, the channelfurther comprising metal wool shielding located within the channel, themetal wool configured to attenuate RF energy in the channel, therebyproviding an electrical shield for the storage space.
 13. The medicalarticle storage container of claim 1 wherein the substrates of the firstand second walls are formed of a plastic having a relatively lowcoefficient of electrical conductivity whereby a lighter wall isprovided.
 14. The medical article storage container of claim 1 whereinthe first wall comprises an opening providing access to the internalstorage space, the medical article storage container also comprising adoor located at an outer surface of the first wall and covering theopening at one position and uncovering the opening in a second position,the door comprising electrically conductive material on an inner surfacecoextensive with the size of the door to electrically mate with theelectrical component of the first wall to provide an RF shield acrossthe opening of the first wall as part of a Faraday cage, the first wallfurther comprising a first portion of a tortuous path seal located aboutthe opening of the first wall, and the door comprising a second portionof a tortuous path of a complementary shape to that of the portion onthe wall, the first portion of the tortuous path configured to acceptthe portion of the tortuous path of the door when the door is in theclosed position such that the tortuous path is completed and thetortuous path seal is formed when the door is in the closed position,whereby both a portion of a Faraday cage is provided by the electricalcontact of the door with the electrical component of the opening and atortuous path seal is provided when the door is in the closed position.15. The medical article storage container of claim 14 wherein thetortuous path seal has a size selected to attenuate energy at anoperating frequency in the storage space, and the tortuous path sealcomprises a bend in which is located electrical shield foam held inplace with an electrically conductive adhesive.
 16. The medical articlestorage container of claim 14 further comprising a drawer slidablylocated in the opening of the first wall and movable into and out of thestorage space, the drawer having a front wall that is larger than theopening in the first wall of the container which comprises the door, thefront wall of the drawer being movable to a closed position in relationto the medical article container at which the front wall of the drawermoves into contact with the first wall and covers the opening; whereinthe drawer is formed of an electrically nonconductive material; whereinthe drawer front wall includes an electrically conductive componentcoexistent with the front wall and configured so that when the drawer isin the closed position, the electrically conductive component of thefront wall of the drawer is placed into physical and electrical contactwith the electrically conductive component of the first wall in whichthe opening is formed to provide a portion of a Faraday cage around thestorage space; wherein the front wall of the drawer further includes aportion of a tortuous path located about edges of the front wall;wherein the first wall of the medical article container includes asecond portion of a tortuous path located about the opening in the firstwall and having a shape that is complementary to the tortuous pathportion disposed about edges of the front wall of the drawer configuredso that when the drawer is closed, the two portions of the tortuous pathmate and form a tortuous path seal thereby shielding the storage spacefrom leakage of RF energy out of and into the storage space.
 17. Themedical article storage container of claim 14 wherein the tortuous pathlocated about the front wall of the drawer has a bend configured toattenuate electrical energy.
 18. The medical article storage containerof claim 1 further comprising a first container module having a falsebottom under which are located an RFID reader and an RFID probe andantenna, and comprising a second module containing the internal storagespace coupled to the first module, the RFID reader and RFID probe andantenna configured to be usable with different sizes of second moduleattached to the first module of the container.
 19. The medical articlestorage container of claim 18 wherein the second module is attached tothe first module at a joint seam, the container further comprising anRFID shielding rib located over the joint seam and providing a Faradaycage shield and a tortuous path seal at the joint seam.
 20. A method ofshielding an internal storage space of a medical article storagecontainer from RF energy leakage out of and into the internal storagespace, comprising: surrounding the internal storage space with aplurality of walls, the walls having a plastic substrate with anembedded electrically conductive component that is coextensive with thesubstrate; connecting together the coextensive electrically conductivecomponents of adjacent walls at joint seams, wherein each wall has ajoining edge configured to mate physically and electrically with ajoining edge of another wall to form a joint seam, thereby providingelectrically conducting walls located completely around the internalstorage space operating as a Faraday cage to attenuate RF energy andshield the internal storage area from leakage of RF energy; and formingan RF tortuous path seal at each joint seam through connecting togethera first portion of an RF tortuous path located at a first wall at thejoint seam with a complementary portion of an RF tortuous path locatedat a second wall at the same joint seam as the first and second wallsare mated together, wherein connecting together the first andcomplementary portions of the RF tortuous path provides a complete RFtortuous path configured to attenuate RF energy; thereby forming aFaraday cage around the entire internal storage area and formingtortuous path seals at the joint seams of the walls when connecting thewalls together; whereby the internal storage area is shielded againstthe leakage of RF energy out of the internal storage area and RF energyinto the storage area by both a Faraday cage and tortuous path seals.